Light-sensitive silver halide photographic elements generally comprise one or more light-sensitive silver halide emulsion layers coated on a support and, if required, one or more light-insensitive auxiliary layers such as subbing layers, intermediate layers, antihalation layers, filter layers and protective layers. As the binders for these constituting layers of the photographic elements, hydrophilic colloids are generally used such as gelatin, gelatin derivatives (such as carbamylated gelatins, acylated gelatins and phthalated gelatins), gelatins graft polymerized with vinyl monomers (such as acrylic acid, methacrylic acid and acrylonitrile), alginic acid, colloidal albumin, cellulose derivatives (.such as carboxymethyl cellulose and hydroxyethyl cellulose), synthetic hydrophilic binders (such as polyvinyl alcohol, polyacrylamide and polyvinylpyrrolidone) and other water-soluble or water-penetrable polymers known in the art, used alone or in mixture of two or more thereof.
It is known that hydrophilic colloids of the photographic elements, as well as aqueous solutions of said hydrophilic colloids, are susceptible to microbial contamination by microorganisms such as bacteria, yeasts and fungi. The microbiological growth causes physical and sensitometric defects in the silver halide photographic elements which are visible upon exposure and processing of said elements.
To prevent or inhibit microbiological growth, it is known to add a biocide into the coating compositions or the silver halide photographic elements. Many biocides have been used in the field of silver halide photography to prevent the aqueous gelatin solutions and the photographic elements from being attacked by bacterial action. Examples of biocides include phenol compounds (such as phenol, thymol, pentachlorophenol, cresol, p-chloro-m-xylenol), aldehydic compounds (such as formaldehyde, glutaraldehyde, paraformaldehyde), acid compounds (such as benzoic acid, sorbic acid, mucochloric acid, mucobromic acid), esters of p-hydroxybenzoic acid (such as methyl-p-hydroxybenzoate, butyl-p-hydroxybenzoate), rare earth salts, amines, disulfides, heterocyclic compounds (such as thiazinium salts, thiazolinones, benzimidazoles), quaternary ammonium salts and organic mercury compounds, used alone or in combination thereof. Combinations of biocides are described, for example, in U.S. Pat. No. 4,923,790 (thiazolylbenzimidazoles combined with phenol compounds and/or thiazolinones), JP 63-257747 (hydroxyalkylphenyl ethers and benzothiazolinones), JP 03-130759 (hydroxyalkyphenyl ethers and esters of p-hydroxybenzoic acid), and DD 281,265 (esters of p-hydroxybenzoic acid and alkyl- or aryl-sulfonates).
Some of the above mentioned biocides must be used in large amounts to be effective. Others have a disagreeable smell, are toxic or irritants. Still others affect the sensitometric properties of the photographic elements and produce fog in the photographic emulsions.